This application claims priority to an application entitled xe2x80x9cDevice and Method of Compensating for Degradation of Received Signalxe2x80x9d filed in the Korean Industrial Property Office on Jul. 7, 1999 and assigned Serial No. 99-27273, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to a digital television receiver, and in particular, to a device and method of compensating for receiving degradation of a terrestrial digital television signal transmitted over a multipath channel.
2. Description of the Related Art
An antenna mounted on a digital television (DTV) receiver should be optimally located in order to receive a television signal, in a best condition, transmitted from a terrestrial broadcasting station. A technology for optimizing an antenna position of a digital television receiver is disclosed in U.S. Pat. No. 5,574,509, entitled xe2x80x9cAntenna Orientation System for Digital TV Receiverxe2x80x9d. FIG. 1 shows a digital television receiver having a positionable antenna disclosed in U.S. Pat. No. 5,574,509.
The digital TV receiver disclosed in U.S. Pat. No. 5,574,509 calculates a signal-to-noise ratio (SNR) for a field sync duration existing in a received signal, to display a quality of the received signal using an on-screen display, so as to enable the user to adjust the position of the antenna. When a digital television broadcast is transmitted from one transmitter, it is possible to adjust the antenna position in the above method. However, when the television broadcasts are transmitted over various channels from several transmitters, as in the existing National Television System Committee (NTSC) broadcasting, an optimal antenna position for one broadcast may be the worst antenna position for another broadcast. That is, since the position of the receiving antenna determines the characteristics of a signal receiving path, a variation in the position of a transmitter affects a channel environment of each broadcast. Therefore, it is necessary to change the antenna position according to the channels in order to receive several broadcasts.
Accordingly, it is not possible to set the position of the receiving antenna based on a specific broadcast only. Instead, it is preferable to set the position of the receiving antenna to be able to receive many different broadcasts, if possible. However, in some cases, the antenna position may not be matched to a transmission position of a presently received broadcast, thereby degrading a quality of the received signal. In this case, it is necessary to compensate for degradation of the received signal for each channel to maintain the optimal receiving condition.
It is therefore, an object of the present invention to provide a device and method for maintaining the best quality of a signal received over a multipath channel without changing an antenna position in a television receiver system.
It is another object of the present invention to provide a device and method of compensating for signal degradation occurring due to deviation of the antenna position from an optimal antenna position before demodulation of a carrier in a digital television receiver.
In accordance with one aspect of the present invention, a device for compensating for degradation of a received signal in a digital television receiver comprises a pre-distortion filter delaying and gain controlling a digital IF signal according to an input parameter control signal; a synchronizer for demodulating a baseband signal by using a pilot signal included in an output signal of the pre-distortion filter, and restoring timing; a channel equalizer for canceling multipath distortion occurring while a television signal passes a transmission channel; and a controller for outputting a parameter control signal such that a filter tap energy output from the channel equalizer becomes a maximum.
In accordance with another aspect of the present invention, a method of compensating for degradation of a received signal in a television receiver having a pre-distortion filter comprises searching received channels upon receipt of a parameter control command; detecting a condition of a received signal while varying a parameter coefficient of the pre-distortion filter in the searched channel; storing a parameter coefficient representing an optimal receiving condition as an optimal parameter coefficient value for a corresponding channel; and reading an optimal value for the corresponding channel whenever selecting a channel out of the searched channels, to compensate for degradation of a received signal.